412 
Recent  British  Weather. 
drizzle,  the  other  cold  and  wet  at  first,  then  dry  and  brilliantly 
hot : the  results  produced  would  not  only  be  widely  different, 
but  they  would  also  be  different  according  to  the  characters  of 
the  months  which  had  preceded  them. 
Fortunately  there  is  a tendency  in  climate  to  take  up,  and 
hold  for  a considerable  time,  types  of  weather.  Cold  and  wet 
generally  go  together  in  summer,  while  warmth  and  wet  go 
together  in  winter,  and  there  are  several  similar  connections 
which  might  be  mentioned — and  hence  we  shall  find  that,  in 
spite  of  all  drawbacks,  actual  numerical  data  will  agree  with 
popular  impressions  as  regards  marked  seasons,  and  hence  may  be 
trusted  as  correcting  doubtful  opinions  respecting  ordinary  ones. 
In  the  present  notice  it  will  tend  to  simplify  matters  if  I 
separate  the  consideration  of  the  two  principal  factors  of  climate, 
heat  and  rainfall. 
Tempekatuke. 
Thanks,  chiefly  to  Mr.  Buchan,  but  also  to  the  observers  who 
furnished  the  data,  we  possess  now  a very  fairly  approximate 
knowledge  of  the  average  temperature  of  each  month,  and  of 
the  year,  over  the  whole  of  the  British  Islands.  Extreme 
accuracy  in  the  present  paper  is  not  needed,  but  rather  a broad 
general  view  of  the  facts,  and  this  may  be  given  very  briefly. 
The  mean  annual  temperature  of  Penzance  may  be  taken  as 
52  \ and  1°  may  be  deducted  for  each  hundred  miles  further 
north — e.g.,  York  is  about  260  miles  north  of  Penzance,  and 
Edinburgh  about  410.  Therefore 
° O 
Penzance 52 ‘0  Penzance 52 '0 
Correction  for  260  miles  = — 2 ■ 6 Correction  for  410  miles  — 4 • 1 
Mean  temp,  of  York  ..  ..  49’4  Mean  temp,  of  Edinburgh  ..  47‘9 
Mr.  Buchan’s  Map  gives  ..  49 ‘0  Mr.  Buchan’s  Map  gives  ..  47 "7 
Agreements  quite  near  enough  for  ordinary  purposes. 
There  is  another  circumstance  which  affects  temperature 
quite  as  much  as  latitude,  and  it  is  the  altitude  of  the  locality 
above  the  sea-level.  Everybody  has  a vague  idea  that  high 
localities  are  cold  ; but  everybody  does  not  know  the  precise 
amount  of  cooling  due  to  any  given  altitude — it  may  be  taken 
as  1°  for  each  300  feet. 
Flence  follows  the  rough  general  rule  that  every  300  feet  of 
elevation  is  equivalent  to  going  100  miles  further  north  ; and 
thus  we  see  one  reason  why  the  high  lands  (1000  to  2000  or 
more  feet)  of  Yorkshire  and  Derbyshire  cannot  bring  to  per- 
fection crops  and  fruits  which  flourish  on  the  low  lands  of  the 
north  of  Scotland. 
